In liquid chromatography, a sample dissolved in eluent, mixture of solvents, as a mobile phase moves through a stationary phase packed in a column. The time for components of the sample fed into the column to flow through the column varies from one component to another, due to difference in interaction with the stationary phase and affinity for the mobile phase. As a result, components contained in the sample are separated when discharged from the column. A component having a stronger interaction with the stationary phase or a weaker affinity for the mobile phase is retained longer in the column and discharged later from the column.
Thin layer chromatography (TLC) is also taken place in the same principle as the liquid chromatography described above. In TLC, after a droplet of sample is applied to a thin-layered substance (column packing) serving as a stationary phase, the thin-layered substance is dipped in eluent serving as a mobile phase. Then, the thin-layered substance absorbs the eluent together with the sample by capillary action, allowing chromatography by this action. From the results, a retardation factor, retention factor, or rate of flow (Rf) of the sample with respect to the eluent can be determined. It is known that the Rf value thus obtained on TLC using eluent with a given solvent ratio has a correlation to resolution (Rs) value of liquid chromatography.
However, due to lack of definite indication of the correlation between the Rf value and the Rs value, results on TLC are not applied to liquid chromatography. Accordingly, in the existing circumstances, for liquid chromatography to be performed at a better Rs value, following steps are taken. Liquid chromatography is performed at an arbitrary Rf value, first. Then, based on the obtained results, an optimum Rs value is sought by changing conditions such as the ratio between polar solvent and non-polar solvent contained in eluent. If a Rf value obtained is, for example, higher than a preset Rf value, then liquid chromatography must be performed again by reducing the proportion of polar solvent to eluent. Thus, it is necessary that liquid chromatography is performed repeatedly with changes by changing the ratio between polar solvent and non-polar solvent until an optimum Rf value for separation of components is sought out. This involves troublesome and time-consuming works and also requires a large amount of eluent.
In the light of the disadvantages mentioned above, the present invention has been made. It is an object of the present invention to provide a liquid chromatograph control apparatus by which chromatography can be performed under such a condition of eluent as an optimum Rf value is obtained without troublesome works, a method for performing liquid chromatography, and a computer program for controlling a liquid chromatograph.